UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.86 Safari/537.36

Steps to reproduce the problem:
1. Open dev tools
2. Select the Device UI
3. See site inside device UI

What is the expected behavior?
When I open the device UI I should see my site in a smaller viewport size, the viewport area should be clearly 

What went wrong?
The new user interface is completely unusable, as a developer who spends 80% of their day inside this part of devtools it makes my eyes physically hurt when I am staring at such a bright UI for extended periods of time.

The UI itself does offer a number of improvements over the old UI however the colours are a major issue and harm the productivity. It is expected that the surround around the site should be dark so that I can clearly see the area that is my site is occupying. A site with a white background practically merges into the background of the tools now.

Upon checking colours using a colour contrast checked I found they also fail colour contrast guidelines
WCAG AA: Fail
WCAG AAA: Fail

Did this work before? N/A 

Chrome version: 50.0.2661.86  Channel: stable
OS Version: OS X 10.11.4
Flash Version: Shockwave Flash 21.0 r0

Switching to the "Dark" theme isn't an option as this then makes the main devtools dark which also has colour contrast issues. 

In addition the argument about making the UI for devtools consistent is invalid in this use case as from a UX point of view its kind of like when you have a lightbox that pops up and everything else around it goes dark. You need to have that clear seperation between the site your debugging and the surround around it.
 

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	Screen Shot 2016-04-27 at 16.05.10.png 1013 KB View Download